JavaNIO-通道10 SocketChannel 使用

SocketChannel

用来表示Socket通道，由于是SelectableChannel子类，支持非阻塞和选择器。

常用API

isConnectionPending 判断此通道上是否正在进行连接操作。

    /**
     *
     *
     * 阻塞通道， IP 不存在
     */
    @Test
    public void test_isConnectionPending_connect() throws Exception {
        SocketChannel socketChannel = SocketChannel.open();
        long begin = 0;
        long end = 0;
        try {
            System.out.println(socketChannel.isConnectionPending());
            socketChannel.connect(new InetSocketAddress("192.168.0.123", 8888));
            socketChannel.isConnectionPending();
        } catch (Exception e) {
            System.out.println(socketChannel.isConnectionPending());
            e.printStackTrace();
        }
    }

    /**
     * 非阻塞通道， IP 不存在
     */
    @Test
    public void test_isConnectionPending_connect2() throws Exception {
        SocketChannel socketChannel = SocketChannel.open();
        long begin = 0;
        long end = 0;
        try {
            System.out.println(socketChannel.isConnectionPending());
            socketChannel.configureBlocking(false);
            socketChannel.connect(new InetSocketAddress("192.168.0.123", 8888));
            System.out.println(socketChannel.isConnectionPending());
        } catch (Exception e) {
            System.out.println(socketChannel.isConnectionPending());
            e.printStackTrace();
        }
    }

    /**
     * 阻塞通道， IP 存在
     */
    @Test
    public void test_isConnectionPending_connect3() throws Exception {
        SocketChannel socketChannel = SocketChannel.open();
        long begin = 0;
        long end = 0;
        try {
            System.out.println(socketChannel.isConnectionPending());
            socketChannel.configureBlocking(false);
            socketChannel.connect(new InetSocketAddress("localhost", 8888));
            System.out.println(socketChannel.isConnectionPending());
        } catch (Exception e) {
            System.out.println(socketChannel.isConnectionPending());
            e.printStackTrace();
        }
    }

    /**
     * 非阻塞通道， IP 存在
     */
    @Test
    public void test_isConnectionPending_connect4() throws Exception {
        SocketChannel socketChannel = SocketChannel.open();
        long begin = 0;
        long end = 0;
        try {
            System.out.println(socketChannel.isConnectionPending());
            socketChannel.configureBlocking(false);
            socketChannel.connect(new InetSocketAddress("localhost", 8888));
            System.out.println(socketChannel.isConnectionPending());
        } catch (Exception e) {
            System.out.println(socketChannel.isConnectionPending());
            e.printStackTrace();
        }
    }

finishConnect 用来在连接失败后重新尝试连接

@Test
    public void test_finishConnect_connect4() throws Exception {
        SocketChannel socketChannel = SocketChannel.open();
        long begin = 0;
        long end = 0;
        try {
            TimeUnit.SECONDS.sleep(1);
            socketChannel.configureBlocking(false);
            boolean result = socketChannel.connect(new InetSocketAddress("localhost", 8888));
            if(result==false){
                while (!socketChannel.finishConnect()){
                    System.out.println("一直在尝试连接");
                    TimeUnit.SECONDS.sleep(1);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

open 同样用来连接服务端，其后设置setOption不会出现预期的效果

 @Test
    public void test_open_connect() throws Exception {
        SocketChannel socketChannel = SocketChannel.open();
        long begin = 0;
        long end = 0;
        try {
            begin = System.currentTimeMillis();
            socketChannel.configureBlocking(false);
            socketChannel.setOption(StandardSocketOptions.SO_RCVBUF,1234);
            //SocketChannel 默认是阻塞模式
            //在发生错误或连接到目标之前， connect （）方法一直是阻塞的
            socketChannel.open(new InetSocketAddress("localhost", 8888));
            end = System.currentTimeMillis();
            System.out.println(end - begin);
        } catch (Exception e) {
            end = System.currentTimeMillis();
            System.out.println(end - begin);
            e.printStackTrace();
        }
    }